Drug Resistant TB Highlights Need for New Drugs to Battle Disease

October 13, 2003

The HIV/AIDS epidemic has proven the most effective way of spreading tuberculosis, or TB, especially in sub-Saharan Africa. The World Health Organization says the number of people infected with both diseases has doubled or tripled in some African countries in the past decade. In the small, east African country of Malawi, the number of TB cases alone has risen to 27,000 in 2001 -- a jump of 500 % from 1985.

Dr. Anne Peterson is assistant administrator for global health at the U.S. Agency for International Development, or USAID: "If you're talking Africa, most of the time when you see TB you should really be thinking about testing for HIV and addressing the TB as part of, potentially, HIV."

Dr. Peterson says TB commonly affects sick people because its bacterium can live inside a person for years without causing any harm. About a third of the world's population, or two billion people, are believed to have this latent form of TB. Once a person contracts HIV, however, the immune system begins to weaken, making it easier for an otherwise harmless infection, like TB, to take hold.

Of course, not everyone with tuberculosis has the HIV virus. For example, India has about one-third of all TB cases in the world -- two million new patients each year -- but the presence of HIV remains very limited.

In Malawi, USAID has been trying to target the problem by opening clinics that offer testing and treatment for both illnesses at the same time. These efforts rely on HIV testing facilities to draw people in for screening. About 150,000 people were tested for HIV last year, which affects an estimated 850,000 people in the country. Once inside, they can also be tested for TB and seek treatment if they test positive.

Dr. Peterson says the so-called ProTEST project has already achieved nationwide coverage in Malawi and has made progress in parts of Uganda. "They're all going to need treatment. If somebody has TB, they need treatment. And even if they are HIV positive, they can be cured of their TB."

Malawi is fortunate because it is one of the few countries to have implemented a TB treatment program sponsored by the World Health Organization, called DOTS. DOTS means directly observed therapy short course. Workers in the program monitor patients to make sure they take their drugs properly for up to nine months and cure themselves of the disease.

The WHO has promoted the DOTS program around the world, saying the combination of drug therapy and patient monitoring can achieve cure rates of 95 % even in the poorest countries.

Despite its success, doctors are concerned that the drugs in the DOTS program are growing too old to remain fully effective against the illness. Over time infections like TB begin to develop resistance to drugs and become immune to treatment. In many cases, drug companies are able to develop a new treatment to overcome the resistance and fight the illness.

The latest TB drug was introduced in the 1960's, however, and very little new research has been done since. Increasingly, strains of TB are emerging that are immune not just to one drug -- but to all the drugs in the DOTS regimen.

Dr. Lee Reichman of the U.S. National TB Center says there is a real danger in multi-drug resistant TB or M.D.R.T.B: “This doesn't happen in nature, MDRTB is man-made”

Dr. Reichman blames the rise of M.D.R.T.B. on people who fail to follow the DOTS regimen. Some patients stop taking their drugs before they are cured, and clinics in some countries don't manage patients properly. Another problem is the black market for drugs, which are often of poor quality.

Health workers say they need cheap drugs that can cure TB faster than the current six- to nine-month regimen and fight resistant strains.

Dr. Steve Projan, director of antibacterial research for U.S-based Wyeth pharmaceutical company, says the call for new TB drugs comes at a bad time. He says drug companies are focusing more research on chronic diseases, like arthritis and heart problems, and not infectious diseases like TB: “It's becoming increasingly difficult to run clinical trials. In an era where pharmaceutical companies are experiencing smaller levels of growth, the investment equation is shifting the balance away from treating acute disease towards chronic disease, towards larger markets.”

Dr. Projan says a major obstacle to developing new drugs is cost: it can take 10 years and at least $900 million to ready one drug for the market. Some of the cost is due to extensive regulations on drug testing in the United States.

Critics of the drug industry contend the major drug companies are to blame. They say drug companies are reluctant to spend money on drugs to fight diseases like TB because most patients are in poor countries.

Jamie Love is director of the Consumer Project on Technology, which studies intellectual property and patents: “We think the current system is broken on many levels, not just for tuberculosis. I think what you see with tuberculosis is symptomatic of a larger problem.”

Mr. Love says drug companies charge high prices for their drugs in order to help finance the development of new drugs. But consumers have no way to make sure companies are spending that money on the most serious health problems.

“Our current system of funding R&D has a lot of inefficiencies,” says Mr. Love. “One of which is this lack of investment in diseases that primarily afflict the poor”

Mr. Love says an alternative is to encourage more government support in the development of new drugs. Public funding in the United States, for example, could help considerably.

The biggest advances in the search for new TB drugs, however, have come from the Global Alliance for TB Drug Development.

Gwynne Oosterbaan is assistant director of public affairs for the TB Alliance: “We know that the market structure alone didn't work in terms of developing a new drug for over 40 years, or else we might have seen a new investment in developing a new and better TB drug. So clearly the world has recognized we need different ways of thinking about diseases that are so widespread.”

Ms. Oosterbaan says the TB alliance was created three years ago with donations from private and public groups to help finance research into promising new drugs. A handful of chemical compounds is already under study. The Alliance hopes to have a new drug ready by 2010 that can reduce the length of TB treatment and combat resistant strains.

Ms. Oosterbaan says these new drugs could increase the number of people who complete the treatment and reduce the possibility of drug resistance. They would also benefit AIDS patients who are already taking anti-retrovirals, or ARVs, to combat the virus: “So if we can shorten the treatment of TB in HIV positive individuals to two months, you improve the treatment of many more people with AIDS, and give them a better chance of continuing their anti-retroviral treatment.”

Back in Malawi, the word of new TB drugs is welcome news to the thousands of people suffering from two life-threatening diseases.